Method and apparatus for automatically adjusting dispensing units of a dispenser

ABSTRACT

A dispensing apparatus includes a frame having a gantry configured to provide movement in the X axis and Y axis directions, and first and second dispensing units coupled to the gantry and configured to dispense material onto a substrate. The second dispensing unit is coupled to the gantry by an automatic adjustment mechanism. The dispensing apparatus further includes a controller configured to control the operation of the gantry, the first dispenser, the second dispenser, and the automatic adjustment mechanism. The automatic adjustment mechanism is configured to move the second dispenser in the X axis and Y axis directions to manipulate a spacing between the first dispensing unit and the second dispensing. Methods of dispensing material on the substrate are further disclosed.

RELATED APPLICATION

This patent application is a continuation patent application of U.S.patent application Ser. No. 15/628,987 filed on Jun. 21, 2017, entitled“METHOD AND APPARATUS FOR AUTOMATICALLY ADJUSTING DISPENSING UNITS OF ADISPENSER,” which is a continuation patent application of U.S. patentapplication Ser. No. 15/165,120 filed on May 26, 2016, entitled “METHODAND APPARATUS FOR AUTOMATICALLY ADJUSTING DISPENSING UNITS OF ADISPENSER,” now U.S. Pat. No. 9,775,250, which is a divisional patentapplication of U.S. patent application Ser. No. 14/041,300 filed on Sep.30, 2013, entitled “METHOD AND APPARATUS FOR AUTOMATICALLY ADJUSTINGDISPENSING UNITS OF A DISPENSER,” now U.S. Pat. No. 9,374,905, all ofwhich are hereby incorporated by references in its entirety for allpurposes.

BACKGROUND OF THE INVENTION 1. Field of the Invention

The present disclosure relates generally to methods and apparatus fordispensing a viscous material on a substrate, such as a printed circuitboard, and more particularly to a method and an apparatus for dispensingmaterial on a substrate with enhanced efficiency and accuracy.

2. Discussion of Related Art

There are several types of prior art dispensing systems used fordispensing precise amounts of liquid or paste for a variety ofapplications. One such application is the assembly of integrated circuitchips and other electronic components onto circuit board substrates. Inthis application, automated dispensing systems are used for dispensingdots of liquid epoxy or solder paste, or some other related material,onto circuit boards. Automated dispensing systems are also used fordispensing lines of underfill materials and encapsulents, which may beused to mechanically secure components to the circuit board. Exemplarydispensing systems described above include those manufactured anddistributed by Speedline Technologies, Inc. of Franklin, Mass.

In a typical dispensing system, a pump and dispenser assembly, referredto as a dispensing head or unit, is mounted to a moving assembly organtry for moving the pump and dispenser assembly along three mutuallyorthogonal axes (X, Y, Z) using servomotors controlled by a computersystem or controller. To dispense a dot of liquid on a circuit board orother substrate at a desired location, the pump and dispenser assemblyis moved along the co-planar horizontal X and Y axes until it is locatedover the desired location. The pump and dispenser assembly is thenlowered along the perpendicularly oriented vertical Z axis until anozzle/needle of the pump and dispenser assembly is at an appropriatedispensing height over the substrate. The pump and dispenser assemblydispenses a dot of liquid, is then raised along the Z axis, moved alongthe X and Y axes to a new location, and is lowered along the Z axis todispense the next liquid dot. For applications such as encapsulation orunderfilling as described above, the pump and dispenser assembly istypically controlled to dispense lines of material as the pump anddispenser are moved in the X and Y axes along the desired path of thelines.

The production rate of such dispensing systems, in some cases, may belimited by the rate at which a particular dispense pump assembly canaccurately and controllably dispense dots or lines of material. In othercases, the production rate of such systems may be limited by the rate atwhich parts can be loaded into and out of the machine. In still othercases, the production rate of such systems may be limited by processrequirements, such as the time required to heat a substrate to aparticular temperature, or the time required for a dispensed material toflow, as in underfill applications. In all cases and applications, thereis some limit to the throughput capability of a single dispense system.

During the manufacture of integrated circuits, production requirementsoften exceed the throughput capabilities of a single dispensing system.To overcome the throughput limitations of a single dispensing system,various strategies are applied to improve the production process. Forexample, U.S. Pat. Nos. 7,833,572, 7,923,056 and 8,230,805, which areincorporated herein by reference in their entirety for all purposes, areeach directed to systems and methods for simultaneously dispensingmaterial with a dispenser having multiple dispensing units. The systemsand methods disclosed in these patents teach adjusting a spacing betweenadjacent dispensing units by using an adjustable bracket.

SUMMARY OF THE INVENTION

One aspect of the disclosure is directed to a dispensing apparatuscomprising a frame including a gantry configured to provide movement inthe X axis and Y axis directions, a support coupled to the frame, thesupport being configured to support at least one electronic substrateunder the gantry, a first dispensing unit coupled to the gantry, thefirst dispensing unit being configured to dispense material, a seconddispensing unit coupled to the gantry by an automatic adjustmentmechanism, the second dispensing unit being configured to dispensematerial, and a controller configured to control the operation of thegantry, the first dispenser, the second dispenser, and the automaticadjustment mechanism. The automatic adjustment mechanism is configuredto move the second dispenser in the X axis and Y axis directions tomanipulate a spacing between the first dispensing unit and the seconddispensing.

Embodiments of the dispensing apparatus further may include an imagingsystem coupled to one of the frame and the gantry. The imaging systemmay be configured to capture at least one image of a first pattern and asecond pattern, the second pattern being substantially identical to thefirst pattern. The imaging system further may be configured to verifywhether the first pattern and the second pattern are properly positionedon the support with respect to one another based on the at least onecaptured image to permit and configured to enable the dispensingapparatus to perform simultaneous dispense operations of the firstdispensing unit on the first pattern and the second dispensing unit onthe second pattern. The automatic adjustment mechanism further mayinclude a linear bearing secured to the gantry and a mounting block,configured to ride along the linear bearing, coupled to the seconddispensing unit. The automatic adjustment mechanism further may includea first linear drive motor assembly configured to move the mountingblock along the linear bearing. The first linear drive motor assemblymay include a ball screw driven linear actuator, which is driven by amechanically coupled motor. The automatic adjustment mechanism furthermay include a first bracket secured to the mounting block, the firstbracket extending in a direction perpendicular to a direction of thelinear bearing, and a second bracket secured to the second dispensingand configured to ride along the first bracket. The automatic adjustmentmechanism further may include a second linear drive motor assemblyconfigured to move the second bracket along the first bracket. Thesecond linear drive motor assembly may include a ball screw drivenlinear actuator, which is driven by a mechanically coupled motor. Foreach of the first dispensing unit and the second dispensing unit, theautomatic adjustment assembly further may include a Z drive mechanismconfigured to support and lower the dispensing unit when performing adispense operation with the first dispensing unit.

Another aspect of the present disclosure is directed to a method ofdispensing viscous material on an electronic substrate. In oneembodiment, the method comprises: delivering a first electronicsubstrate pattern to a dispense position; delivering a second electronicsubstrate pattern to a dispense position; moving first and seconddispensing units over the first and second electronic substrate patternswith a gantry configured to move the first and second dispensing unitsin an X axis direction and a Y axis direction; aligning the firstelectronic substrate pattern with the first dispensing unit and thesecond electronic substrate pattern with the second dispensing unit withan automatic adjustment mechanism configured to move the seconddispensing unit in the X axis direction and the Y axis direction apredetermined distance from the first dispensing unit; dispensingmaterial from the first dispensing unit at desired locations on thefirst electronic substrate pattern; and dispensing material from thesecond dispensing unit at desired locations on the second electronicsubstrate pattern.

Embodiments of the method further may include calibrating a distancebetween first and second dispensing units and a camera. Dispensingmaterial from the first dispensing unit at desired locations on thefirst electronic substrate pattern may include lowering the firstdispensing unit toward the first electronic substrate pattern.Dispensing material from the second dispensing unit at desired locationson the second electronic substrate pattern may include lowering thesecond dispensing unit toward the second electronic substrate pattern.The predetermined distance may be determined by identifying a firstpoint of reference associated with the first electronic substratepattern and a second point of reference associated with the secondelectronic substrate pattern. If the at least two patterns are notproperly positioned, the method further may include simultaneouslyperforming a first dispense operation on a first pattern of the at leasttwo patterns and performing a second dispense operation on a secondpattern of the at least two patterns. Simultaneously performing firstand second dispense operations includes dynamically positioning thesecond dispensing unit with the automatic adjustment mechanism.

The present disclosure will be more fully understood after a review ofthe following figures, detailed description and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are not intended to be drawn to scale. In thedrawings, each identical or nearly identical component that isillustrated in various figures is represented by a like numeral. Forpurposes of clarity, not every component may be labeled in everydrawing. In the drawings:

FIG. 1 is a side schematic view of a dispenser of an embodiment of thedisclosure;

FIG. 2 is a top schematic view of a dispenser of another embodiment;

FIG. 3 is a perspective view of a portion of a dispenser of anotherembodiment of the disclosure;

FIG. 4 is an enlarged top plan view of the dispenser shown in FIG. 3;and

FIG. 5 is a top plan view of two offset parts provided in an Auer boat.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

For the purposes of illustration only, and not to limit the generality,the disclosure will now be described in detail with reference to theaccompanying figures. This disclosure is not limited in its applicationto the details of construction and the arrangement of components setforth in the following description or illustrated in the drawings. Theteachings disclosed herein are capable of other embodiments and of beingpracticed or being carried out in various ways. Also the phraseology andterminology used herein is for the purpose of description and should notbe regarded as limiting. The use of “including,” “comprising,” “having,”“containing,” “involving,” and variations thereof herein, is meant toencompass the items listed thereafter and equivalents thereof as well asadditional items.

As mentioned above, in some cases, multiple independent dispensingsystems are sometimes used to increase the production of dispenseoperations. This solution is often expensive, requiring multiplemachines, additional manufacturing space and in some cases multiplemachine operators. In typical operations, manufacturing floor space isboth limited and expensive. It is therefore desirable to reduce the“footprint” of each manufacturing system on the manufacturing floor andto reduce the number of separate machines that need to be operated andmaintained.

For some applications, multiple instances of the same circuit patternare fabricated on a common substrate. A common example is a circuitpattern for a cell phone, wherein four or more patterns may be disposedon a single substrate. In such cases, there is often a fixed and uniformoffset between the multiple instances of the circuit patterns, which maybe disposed on a common substrate and separated from one another aftercompletion along perforations. Furthermore, it is known in the industrythat a dispensing system with multiple dispensing units or pumps may beutilized to increase throughput. In such systems, the offset distancebetween the multiple dispensing pumps may be adjusted to besubstantially the same as the offset distance between the multiplecircuit distances, and if the accuracy of this offset adjustment iswithin the accuracy requirements of the resultant dispense pattern, thenthe multiple dispensing pumps can be positioned simultaneously by asingle X, Y, Z gantry and operated simultaneously. The presentdisclosure is directed to a system for automatically adjusting theoffset distance between the multiple dispensing pumps.

When a dispensing system is presented with a substrate or component tobe dispensed upon, it is typical that an automatic vision system is usedto locate and calibrate the actual position of the part and/or criticalfeatures within the part. This locating and calibrating allows thesystem to compensate for variations in either the substrate or componentitself or in the fixing of the substrate or component relative to thecoordinate system of the dispensing unit positioning system.

When multiple dispensing units or heads are utilized in parallel toachieve a high collective throughput, e.g., dispensing on two substratesat the same time, it is typical that the multiple dispensing units areprogrammed to perform substantially the same task on substantiallyidentical components. However, because of slight variations in eitherthe components themselves or in the fixing of the components relative tothe positioning systems, corrections may need to be appliedindependently to each of the multiple dispense units. Since thesecorrections are unique to each of the multiple dispense units, it isnecessary that each of the dispensing units be independently positionedrelative to its substrate. Accordingly, dispensers configured withmultiple dispensing units are more adapted for coarse dispensingapplications in which accurate dispensing is not critical.

One prior art system achieves high throughput by utilizing multipleindependent dispensing units and is described in U.S. Pat. No.6,007,631, which is incorporated herein by reference. This dispensingsystem utilizes multiple independent dispensing units or heads. Each ofthe multiple dispensing units is mounted on a separate positioningsystem and operates over an independent work area.

One other prior art system achieves high throughput by utilizingmultiple units and multiple pallets of parts and is described inprovisional U.S. patent application Ser. No. 60/432,483, filed Dec. 11,2002, now abandoned, and also in U.S. patent application Ser. No.10/661,830, filed Sep. 12, 2003, now abandoned, both of which areincorporate herein by reference.

It is desirable to achieve at least some of the throughput advantages ofthe multiple dispense units or heads while still providing the size andcost advantages of a single dispense system. Embodiments of thedisclosure described below achieve the throughput advantages of priorart dispensers described above while further reducing the footprint andcost by positioning multiple dispensing units above the surface of thesubstrates with a common gantry. Specifically, embodiments of thedisclosure are directed to dispensing units, methods of dispensing anddispensing systems that contain methods and apparatus of the disclosure.Embodiments of the disclosure can be used with dispensing systemplatforms offered under the brand name CAMALOT® by SpeedlineTechnologies, Inc. of Franklin, Mass.

FIG. 1 schematically illustrates a dispenser, generally indicated at 10,used to dispense a viscous material (e.g., adhesive, encapsulent, epoxy,solder paste, underfill material, etc.) or a semi-viscous material(e.g., soldering flux, etc.), or a substantially non-viscous material(e.g., an ink) onto an electronic substrate 12, such as a printedcircuit board or semiconductor wafer. The substrate 12 may embody anytype of surface or material upon which dispensing is required, and mayinclude any number of patterns. The dispenser 10 includes first andsecond dispensing units or heads, generally indicated at 14 and 16,respectively, and a controller 18 to control the operation of thedispenser. Although two dispensing units are shown, it should beunderstood that more than two dispensing units may be provided.

The dispenser 10 also includes a frame 20 having a base 22 forsupporting the substrate 12 and a gantry 24 movably coupled to the frame20 for supporting and moving the dispensing units 14, 16. As is wellknown in the art of printed circuit board fabrication, a conveyor system(not shown) may be used in the dispenser 10 to control loading andunloading of substrates to and from the dispenser. The gantry 24 can bemoved using motors under the control of the controller 18 in the X axisand Y axis directions to position the dispensing units at predeterminedlocations over the substrate.

Referring to FIG. 2, the gantry 24 may be configured to include aleft-hand side rail 26, a right-hand side rail 28 and a beam 30 thatextends between the two side rails. The beam 30 is configured to move ina Y axis direction along the side rails 26, 28 to achieve Y axismovement of the dispensing units 14, 16. X axis movement of thedispensing units 14, 16 is achieved by a carriage device 32 mounted onthe beam 30. Specifically, the carriage device 32 houses the dispensingunits 14, 16 and is configured to move along the length of the beam 30in the X axis direction to move the dispensing units over desiredlocations of the substrate 12 positioned on the base 22. In a certainembodiment, movement of the gantry 24 (i.e., movement of the beam 30 andthe carriage device 32) in the X-Y plane may be achieved by employingball screw mechanisms driven by respective motors as is well known inthe art.

In one embodiment, the platform dispenser 10 described herein may embodyan FX-D® dispensing system sold by Speedline Technologies, Inc. ofFranklin, Mass. In another embodiment, the platform dispenser may embodya SMARTSTREAM® dispensing system, which is also sold by SpeedlineTechnologies, Inc.

The dispensing units 14, 16, as mentioned above, are capable ofachieving Z axis movement by means of independent Z drive mechanisms,which are designated at 34, 36, respectively, in FIG. 2. The amount of Zaxis movement may be determined by measuring the distance between thetip of a needle (not shown) of one of the dispensing units 14 and/or 16and the substrate 12. When moving, one or both of the dispensing units14, 16 may be positioned at a nominal clearance height above thesubstrate 12. The clearance height may be maintained at a relativelyconsistent elevation above the substrate 12 when moving from onedispense location to another dispense location. Upon reaching apredetermined dispense location, the Z drive mechanism 34, 36 lowers itsrespective dispensing unit 14, 16 to the substrate so that dispensing ofmaterial on the substrate 12 may be achieved.

In certain embodiments, a common gantry that moves both of thedispensing units together may control the dispensing units. Thus, asingle Z drive mechanism may be provided. This configuration isparticularly suited for dispensing units that stream or launch viscousmaterial onto the substrate. In one embodiment, the dispensing unit maybe of the type disclosed in U.S. patent application Ser. No. 11/707,620,entitled METHOD AND APPARATUS FOR DISPENSING VISCOUS MATERIAL ON ASUBSTRATE, filed Feb. 16, 2007, which claims priority to U.S.Provisional Patent Application Ser. No. 60/856,508, entitled METHOD ANDAPPARATUS FOR DISPENSING A VISCOUS MATERIAL ON A SUBSTRATE, filed Nov.3, 2006, both of which are incorporated herein by reference. With thedispensing unit disclosed in the non-provisional and provisionalapplications, viscous material streams onto the substrate betweenpredetermined starting and stopping points. In another embodiment, thedispensing unit may be of the type disclosed in U.S. Pat. No. 5,747,102,entitled METHOD AND APPARATUS FOR DISPENSING SMALL AMOUNTS OF LIQUIDMATERIAL, issued May 5, 1998, which is incorporated herein by reference.With the dispensing unit disclosed in this patent, viscous material islaunched at a predetermined location on the substrate. The dispensingunits that stream or launch viscous material may be referred to asnon-contact dispensing units in which Z axis movement is not required,but may be provided.

In one embodiment, to measure the height of the needle of the dispensingunit at a desired elevation above the substrate, there is provided asystem for measuring the height of the dispenser needle above thesubstrate in the Z axis direction. In some height (or distance)measuring systems, physical contact is made between the measuring systemand the surface. One such height measuring system is described in U.S.Pat. No. 6,093,251, entitled APPARATUS FOR MEASURING THE HEIGHT OF ASUBSTRATE IN A DISPENSING SYSTEM, which is assigned to the assignee ofthe present disclosure, and is incorporated herein by reference.Specifically, U.S. Pat. No. 6,093,251 discloses a measuring probe thatis extendable between a reference point and a location on the substrateto measure the height of the substrate. In other height measuringsystems, a laser light source and an optical sensing system are combinedto measure the position of an object without making physical contact. Anexample of a non-contact measuring system is manufactured anddistributed by Micro-Epsilon Messtechnik GmbH of Ortenburg, Germany. Inother embodiments, the height measuring system can be incorporated tofacilitate the measurement of and compensation for variations in thevertical position of the top surface of the substrate.

Still referring to FIG. 2, the dispensing units 14, 16 are moved overthe substrate 12 in such a manner to perform a dispense operation withone or both of the dispensing units. However, prior to dispensing, theposition of the substrate 12 with respect to the dispensing units 14, 16is determined so that accurate dispensing may take place. Specifically,the carriage device 32 includes an optical element or camera 38 that isconfigured to take an image of the substrate 12. Although the camera 38is shown to be mounted on the carriage device 32, it should beunderstood that the camera may be separately mounted on the beam 30 oron an independent gantry. The camera 38 may be referred to herein as a“vision system” or an “imaging system.” To align the substrate 12 withthe dispensing units 14, 16 and gantry 24, images of at least twofiducials (44, 46) are taken by the camera 38. If the substrate 12 isout of position, the gantry 24 may be manipulated to account for theactual position of the substrate. In one embodiment, the camera 38 maybe calibrated to determine camera-to-needle offset distances for each ofthe dispensing units 14, 16 in a manner described in greater detailbelow.

Referring to FIG. 3, a dispenser is generally indicated at 100. Asshown, the dispenser 100 is configured to dispense a viscous material(e.g., adhesive, encapsulent, epoxy, solder paste, underfill material,etc.) or a semi-viscous material (e.g., soldering flux, etc.), or asubstantially non-viscous material (e.g., an ink) onto an electronicsubstrate 102, such as a printed circuit board or semiconductor wafer.The substrate 102 may embody any type of surface or material upon whichdispensing is required. As shown, the substrate 102 includes twopatterns, indicated at 102 a and 102 b. The dispenser 100 includes firstand second dispensing units or heads, generally indicated at 104 and106, respectively, which are secured to a gantry, such as gantry 24 ofdispenser 10, and operated under the control of a controller, such ascontroller 18, to control the operation of the dispenser. Although twodispensing units 104, 106 are shown, it should be understood that morethan two dispensing units may be provided.

As described above, the dispenser 100 includes a gantry, generallyindicated at 108, which is movably coupled to a frame of the dispenserfor supporting and moving the dispensing units 104, 106. Theconstruction of gantry 108 is substantially similar to the constructionof gantry 24 for dispenser 10. As is well known in the art of printedcircuit board fabrication, a conveyor system (not shown) may be used inthe dispenser 100 to control loading and unloading of substrates to andfrom the dispenser. The gantry 108 can be moved using motors under thecontrol of the controller in the X axis and Y axis directions toposition the dispensing units 104, 106 at predetermined locations overthe substrate 102.

As with gantry 24 of dispenser 10, the gantry may be configured toinclude a beam that extends between two side rails. The beam isconfigured to move in a Y axis direction along the side rails to achieveY axis movement of the dispensing units 104, 106. X axis movement of thedispensing units 104, 106 is achieved by a carriage device 110 mountedon the beam. Specifically, the carriage device 110 supports thedispensing units 104, 106 and is configured to move along a width of thebeam in the X axis direction to move the dispensing units over desiredlocations of the substrate 102 positioned on a base of the dispenser. Ina certain embodiment, movement of the gantry 108 (i.e., movement of thebeam and the carriage device) in the X-Y plane may be achieved byemploying ball screw mechanisms driven by respective motors or otherlinear motion drive components as is well known in the art.

The first dispensing unit 104 and the second dispensing unit 106 arecoupled to the carriage device 110 by a linear bearing 112 secured tothe carriage device 110. In one embodiment, the first dispensing unit104 is fixedly secured to the linear bearing 112 and the seconddispensing unit 106 is coupled to the linear bearing by an automaticadjustment mechanism, which is generally indicated at 114 in FIG. 3. Itshould be understood that the second dispensing unit 106 may be fixed tothe linear bearing 112 and the first dispensing unit 104 may be coupledto the automatic adjustment mechanism 114, and fall within the scope ofthe present disclosure. As shown, the first dispensing unit 104 and thesecond dispensing unit 106 are offset from one another a distance, withthe automatic adjustment mechanism 114 being configured to adjust thedistance by moving the second dispensing unit a relatively smalldistance in the X axis and Y axis directions.

In the shown embodiment, the first dispensing unit 104 is secured to thelinear bearing 112 by a mounting assembly having a mounting block 116,which is secured to the first dispensing unit and to the linear bearing.The mounting assembly associated with the first dispensing unit 104further includes a Z axis movement mechanism, generally indicated at118, which enables the Z axis movement of the first dispensing unit. TheZ axis movement mechanism 118 is particularly suited for lowering thefirst dispensing unit during a dispensing operation, e.g., for anauger-type dispensing unit.

With additional reference to FIG. 4, the automatic movement mechanism114 includes a mounting block 120, which is secured to the seconddispensing unit 106 and configured to ride along the linear bearing 112to provide movement in the X axis direction. The automatic adjustmentmechanism 114 further includes a first motor assembly generallyindicated at 122 configured to move the mounting block 120, and thesecond dispensing unit 106, along the linear bearing 112. In oneembodiment, the first motor assembly 122 includes a ball screw drivenlinear actuator 124, which is driven by a mechanically coupled rotaryservo motor 126 or other electro-mechanical linear drive device. Thus,the automatic adjustment mechanism 114 is capable of adjusting thesecond dispensing unit 106 in the X axis direction while the firstdispensing unit 104 remains stationary. In a certain embodiment, theautomatic adjustment mechanism 114 is capable of providing a relativelyshort amount of X axis movement of the second dispensing unit 106 toprovide fine adjustment of the second dispensing unit relative to thefirst dispensing unit 104.

As mentioned above, the automatic adjustment mechanism 114 is alsocapable of adjusting the second dispensing unit 106 in the Y axisdirection in the manner described below. Specifically, the automaticadjustment mechanism 114 further includes a first bracket 128 secured tothe mounting block 120. As shown, the first bracket 128 extends in adirection perpendicular to a direction of the linear bearing 112 in theY axis direction. The automatic adjustment mechanism 114 furtherincludes a second bracket 130 secured to the second dispensing unit 106and configured to ride along the first bracket 128 thereby providing asmall amount of movement of the second dispensing unit in the Y axisdirection. The automatic adjustment mechanism 114 further includes asecond motor assembly 132 configured to move the second bracket 130along the first bracket 128 thereby moving the second dispensing unit106. In one embodiment, the second motor assembly 132 includes a ballscrew driven linear actuator 134, which is driven by a mechanicallycoupled rotary servo motor 136 or other electro-mechanical linear drivedevice.

Similar to the first dispensing unit 104, the second dispensing unit 106includes a Z axis movement mechanism, generally indicated at 138, whichenables the Z axis movement of the second dispensing unit. The Z axismovement mechanism 138 is particularly suited for lowering the firstdispensing unit during a dispensing operation, e.g., for an auger-typedispensing unit.

As discussed with dispenser 10, the dispenser 100 includes a visionsystem, such the camera 38 of dispenser 10, and the gantry 108 iscapable of moving the camera over the substrate 102 to capture images ofthe substrate to align the substrate with the dispensing units 104, 106.With the assistance of the camera, the second dispensing unit 106 may beautomatically adjusted by the automatic adjustment mechanism 114. Z axismovement of the dispensing units 104, 106 may be achieved by theindependent Z drive mechanisms 118, 138 associated with the first andsecond dispensing units, respectively.

Thus, it should be observed that the dispenser 100 of embodiments of thepresent disclosure is capable of making automatic positional correctionsto multiple dispensing units based on single or multiple vision capturesand calculations required adjustments. The dispenser 100 of embodimentsof the present disclosure enables higher accuracy in dispensing withmultiple dispense units on a single gantry. This enables higherthroughput thus greater value to PCB fabricators. With the evershrinking of electronics and electronics packaging, such PCB fabricatorsare continuously challenged with greater accuracy requirements fromcustomers with higher throughput. The dispenser 100 of embodiments ofthe present disclosure addresses these requirements.

In one embodiment, to make a static one-time adjustment per substratepresented to the dispenser, the vision system and the controller locatesand calculates the distance of one part in a substrate to another partin the same substrate, as well as any rotation of the substrate relativeto the X/Y gantry, and adjust the second dispensing unit one time priorto dispensing simultaneously. In another embodiment, the automaticadjustment mechanism 14 may be utilized to make dynamic adjustmentswhile dispensing separate parts/substrates each indicated at 140 in acarrier, such as an Auer boat 142 shown in FIG. 5, which are notconnected or accurately aligned with each other. In this case, thevision system would locate each part/substrate 140 in the carrier 142and calculate the relative offset and rotation of each part/substrate.The dispenser 100 would then begin dispensing a “master” substratepattern, while simultaneously dispensing other substrates whiledynamically adjusting the other dispensing units relative to the master.

Thus, when two patterns are not properly positioned, or in instances inwhich two substrates are not properly positioned, the method includesimultaneously performing a first dispense operation on the firstpattern (or substrate) with the first dispensing unit 104 and performinga second dispense operation on the second pattern (or substrate) withthe second dispensing unit 106. This may be achieved by dynamicallypositioning the second dispensing unit 106 with the automatic adjustmentmechanism 114 while continuing to dispense with the first and seconddispensing units 104, 106.

The dispenser 100 of embodiments of the invention is capable ofdispensing different patterns simultaneously. In such a method, thegantry 108 carrying the dispensing units 104, 106, as well as theautomatic adjustment mechanism 114 associated with the second dispensingunit, are manipulated to dispense different patterns simultaneously.Specifically, for dynamic adjustment, the two parts 140 illustrated inFIG. 5 are offset within the Auer boat 142. The right-hand, firstdispensing unit 104 is fixed, so a dispensing path of the firstdispensing unit follows the movement of the main gantry 108. Adispensing path of the left-hand, second dispensing unit 106 iscalculated from the vision system and controlled by the automaticadjustment mechanism 114. With this method, lines dispensed by the firstdispensing unit 104 and the second dispensing unit 106 may be drawnsynchronously.

In one embodiment, the automatic adjustment mechanism 114 of thedispenser 100 is capable of moving the second dispensing unit 106 adistance of 50 mm in the X axis direction and a distance of 12 mm in theY axis direction.

In another embodiment, the dispenser 100 can be configured to enable oneor both of the dispensing units 104, 106 to automatically pitch duringsetup.

Accordingly, for a dispenser having multiple dispensing units, thedistance and relative position of each of the multiple dispensing unitsmay be configured to match the distance and relative spacing betweeneach of the multiple substrates or components. After collecting andanalyzing alignment information from an automatic vision alignmentsystem, a first of the multiple dispensing units is positioned over afirst dispense location on the first substrate or component. Afterperforming a dispense operation, the gantry may be manipulated to makeany required X-Y plane position adjustment that may be necessary toalign a second of the multiple dispensing units over the correspondingfirst dispensing location of the second of the multiple substrates orcomponents. Since the distance and relative position between each of themultiple dispense units is substantially similar to, although notnecessarily identical to, the distance and relative position betweeneach of the multiple substrates or components, any such adjustment ofthe gantry will be very small and thus rapidly performed. Each of theremaining multiple dispense units may be similarly utilized to dispensematerial at the corresponding first dispense location on each of theremaining substrates or components before any large X and Y gantrymotion is required. However, if the number of substrates or componentsis greater than the number of dispense units, then the gantry may needto be repositioned to complete the dispensing operations on all of thesubstrates. The method is repeated to dispense each of the second andsubsequent dispense locations. It should be understood that steps may beinterchanged as may be dictated by either throughput or processimprovements.

As discussed above, in one embodiment, the dispensing units may bemounted on separate Z drive mechanisms. This configuration enables theperformance of independent operations when appropriate, including butnot limited to dispensing, cleaning (as by an automatic needle cleaner,for example), purging and calibration (either the X/Y axes position orthe Z axis position). However, it should be noted that the dispenser 50may be particularly suited for non-contact dispensing, such as thestreaming of material from the needle. When configured for non-contactdispensing, the dispensing operation may be performed with the two (ormore) dispensing units that are mounted on a single Z drive mechanism.

With this particular configuration, in one embodiment, the twodispensing units are both positioned over their respective locations onthe two (or more) substrates or a single substrate having two (or more)patterns. Specifically, when positioning the first dispensing unitnearly exactly over a given dispense position on the first substrate,the second dispensing unit is in an approximately correct position overthe second substrate. Next, the first dispensing unit performs a firstdispense operation on the first substrate. Once completed, the seconddispensing unit is moved a minor amount to correct its location over thesecond substrate so as to enable the performance of a second dispenseoperation on the second substrate. Since non-contact dispensing does notrequire a Z axis direction of movement, having the first and seconddispensing units mounted on a common Z drive mechanism does not precludeindependent dispensing from each of the dispensing units.

As discussed above, when determining the offset distance betweenmultiple substrates, or multiple patterns within a single substrate, thecamera may be operated to take images of known reference points, such asfiducials, which are used to determine the offset distance between thesubstrates. However, the offset distance may be determined by theoperator of the dispenser during the set-up of the dispenser based onknown configurations. In addition, as described above, the exact offsetdistance between the substrates is not necessary. A more coarse distancemay be appropriate. Specifically, while a more precise offset distancebetween the substrates would serve to minimize any corrective moverequired of the second dispensing unit (or the first dispensing unit ifthe second dispensing unit is fixed), an imprecise offset distance wouldnot preclude or otherwise negatively impact a precise second dispenseoperation. The actual relative distance between the two or moredispensing units may be measured and therefore corrected forinaccuracies in the setting of the offset distance between thesubstrates with the automatic adjustment mechanism.

In certain embodiments, when dispensing on multiple patterns provided ona single substrate, each pattern may have its own corresponding set oflocal alignment fiducials. Alternatively, the substrate may have one setof global fiducials used to align the entire substrate and thus themultiple patterns at once. In a typical process program, the locationsof many of the dispensing sites are known, generally being definedrelative to the alignment fiducial locations. Accordingly, once theactual locations of the fiducials have been measured using the camera,the actual positions of the many dispense locations may be calculated,including those locations associated with multiple instances of arepeated pattern. Since each of the multiple dispensing units mounted onthe gantry has its own camera-to-needle offset distance, which may beseparately learned or calibrated as described above, and since each ofthe multiple dispensing units may be operated at separate times, theproper position corrections for each and every dispense location may beseparately and accurately applied to each of the multiple dispensingunits.

It should be observed that the dispenser may be operated to performdispense operations with multiple dispensing units that operateindependently from each other. The camera to needle offset distance maybe calibrated by the dispenser, or be selected by the operator of thedispenser. Prior to dispensing, the camera-to-needle offset distancesmay be determined. Additionally, locations of the first and seconddispensing units may be calibrated to determine their respectivelocations prior to dispensing. Finally, the relative offset distancebetween each of the dispensing units may be nominally (not precisely)calculated to match the relative pitch between multiple instances of arepeated substrate pattern.

Thus, an exemplary dispense operation for two substrates or for twosubstrate patterns may consist of the following steps: delivering afirst electronic substrate pattern to a dispense position; delivering asecond electronic substrate pattern to a dispense position; aligning thefirst electronic substrate pattern with a first dispensing unit;positioning the second dispensing unit a predetermined distance from thefirst dispensing unit; dispensing material from the first dispensingunit at desired locations on the first electronic substrate pattern; anddispensing material from the second dispensing unit at desired locationson the second electronic substrate pattern. In certain embodiments, thestep of dispensing material from the first dispensing unit may compriselowering the first dispensing unit toward the first electronic substratepattern. Similarly, the step of dispensing material from the seconddispensing unit may comprise lowering the second dispensing unit towardthe second electronic substrate pattern.

Another exemplary dispense operation may consist of the following steps:delivering first and second electronic substrate patterns to respectivedispense positions; positioning a first dispensing unit over the firstelectronic substrate pattern; positioning a second dispensing unit apredetermined distance from the first dispensing unit; dispensingmaterial from the first dispensing unit at desired locations on thefirst electronic substrate pattern, wherein dispensing material from thefirst dispensing unit comprises lowering the first dispensing unittoward the first electronic substrate pattern; and dispensing materialfrom the second dispensing unit at desired locations on the secondelectronic substrate pattern, wherein dispensing material from thesecond dispensing unit comprises, lowering the second dispensing unittoward the second electronic substrate pattern. In certain embodiments,the predetermined distance is determined by identifying a first point ofreference associated with the first electronic substrate pattern and asecond point of reference associated with the second electronicsubstrate pattern.

Yet another exemplary dispense operation for two substrates may consistof the following steps: (1) calibrating the actual distance between eachof the dispensing units and the camera; (2) identifying the actualpositions of the fiducial locations on a substrate or on multiplesubstrates; (3) moving the first dispensing unit to a first dispenselocation on a first substrate; (4) dispensing at the first dispenselocation on the first substrate; (5) moving the second dispensing unitto the first dispense location on the second substrate, which is a smalland therefore rapidly performed movement; (6) dispensing at the firstdispense location on the second substrate; and (7) repeating steps (3)through (6) for each of the remaining dispense locations on thesubstrates. The foregoing operation may be performed when dispensing ona single substrate having multiple patterns on the substrate.

In other embodiments of the disclosure, a dual-lane conveyor isincorporated into the system to handle work pieces. In such systems, thedispense units continue to dispense on parts fixed on one conveyor lanewhile parts are loaded off of and onto another conveyor lane.

In another example, when the substrates are aligned, or in the form ofmultiple, identical patterns that are aligned with one another on thesubstrate, such with cell phone patterns, rather than engaging the firstdispensing unit to dispense on the first substrate and then the seconddispensing unit to dispense on the second substrate, the first andsecond dispensing units may be operated simultaneously. Thus, withrespect to the two substrates, the first and second dispensing units maybe moved by the beam and the carriage device over spaced apart locationson the substrate, respectively, to dispense on these locations ofrespective substrates. After material is dispensed, the beam and thecarriage device may operated to move the first and second dispensingunits over separate locations, respectively, for performing dispensesimultaneous operations on these locations. This process may be repeatedfor each location until all of the locations on the substrates requiringmaterial are dispensed upon.

As mentioned above, the second dispensing unit may be moved with respectto the first dispensing unit a predetermined distance by the automaticadjustment mechanism, which may be operated to achieve a length that isequivalent to the distance between the first and second substrates. In acertain embodiment, the second dispensing unit may be manually preset toa desired position. Since the patterns on the first and secondsubstrates are identical, the locations on the second substratecorrespond to the locations on the first substrate so that the movementof the dispensing units places the dispensing units above correspondinglocations on the substrates. Z axis movement may be achieved by theindependent Z drive mechanisms associated with the first and seconddispensing units, respectively.

In one embodiment, the camera is configured to capture an image of afirst pattern (e.g., a fiducial or a pattern landmark on the substrate)and to capture an image of a second pattern (e.g., a fiducial or apattern landmark on the substrate). The camera may take one or moreimages of the substrate in order to obtain sufficient information as towhether the first and second patterns are aligned with one another.After taking the image or images, the controller is configured to usethe image or images to verify whether the first pattern and the secondpattern are properly positioned on the support with respect to oneanother based on the image. If properly positioned, the dispensing unitsmay be controlled by the controller to perform simultaneous dispenseoperations of the first dispensing unit on the first pattern and thesecond dispensing unit on the second pattern. As mentioned above, thedispensing units may be non-contact-type dispensing units that arecapable of streaming or launching material onto the substrate.

In the situation where the two patterns are not properly positioned, thedispenser may be operated to accurately dispense material on thepatterns. For example, in one embodiment, the first dispensing unit mayperform all of the dispense operations on the first pattern. Aftercompleting the first pattern, the first dispensing unit or the seconddispensing unit may perform all of the dispense operations on the secondpattern. In another example, the first dispensing unit may perform someof the dispense operations on a first area of the first pattern. Next,the second dispensing unit may perform some of the dispense operationson a first area of the second pattern. After completing the first areasof the first and second patterns, the first and second dispensing unitsmay sequentially dispense material on subsequent areas of the first andsecond patterns in the manner described above.

In another embodiment, if the two patterns are not properly positioned,the method may include simultaneously performing a first dispenseoperation on the first pattern and performing a second dispenseoperation on the second pattern. This may be achieved by dynamicallypositioning the second dispensing unit with the automatic adjustmentmechanism while continuing to dispense with the first and seconddispensing units.

In further examples, the substrate may include three or more patterns,or three or more separate substrates may be provided. With eitherexample, the camera may be configured to capture images of each patternas described above. After taking the images, the controller may beconfigured to use the image or images to determine whether the patternsare sufficiently aligned for simultaneous dispensing. In one embodiment,the dispenser may be configured with any number of dispensing units todispense on the patterns. In other embodiments, the dispenser may beconfigured with two dispensing units as disclosed above, with onedispensing unit (e.g., dispensing unit 14) dispensing on the firstpattern and the other dispensing unit (e.g., dispensing unit 16)simultaneously dispensing on the third pattern. This approach may beparticularly desirable when adjacent patterns are positioned too closeto one another, thereby prohibiting the dispensing units from being ableto operate over adjacent patterns due to the relatively large sizes ofthe dispensing units. Once dispensing on the first and third patterns iscompleted, the dispenser may be configured to move the dispensing unitssuch that the first dispensing unit is positioned over the secondpattern and the second dispensing unit is positioned over the fourthpattern, if provided. This sequence of operation may continue untildispensing operations are performed on all of the patterns. For an oddnumber of patterns, the first dispensing unit may be configured todispense material on the last pattern, while the second dispensing unitremains stationary.

It is further contemplated that when using more than two dispensingunits, that this approach of simultaneous dispensing on every otherpattern may be employed. For example, when using three dispensing units,the first, third and fifth patterns may be dispensed upon simultaneouslyby the first, second and third dispensing units, respectively. Afterdispensing on these patterns, the dispensing units may be moved so thatdispensing occurs on the second, fourth and sixth patterns with thefirst, second and third dispensing units, respectively.

In an exemplary embodiment, a method of dispensing material may includedelivering an electronic substrate to a dispense position, theelectronic substrate having at least two identical patterns, capturingat least one image of the at least two patterns, determining whether theat least two patterns are properly positioned to perform simultaneousdispense operations on the at least two patterns based on the capturedimage, and performing simultaneous dispense operations on the at leasttwo patterns if the two patterns are properly positioned.

Dispensing material may include positioning a first dispensing unit overa first location of a first pattern and positioning a second dispensingunit over a first location of a second pattern. As discussed above, thesecond dispensing unit may be spaced from the first dispensing unit apredetermined distance. Specifically, material may be dispensed from thefirst and second dispensing units on respective first locations of thefirst and second patterns. Once dispensing takes place, the firstdispensing unit is moved over a second location of the first pattern andthe second dispensing unit is simultaneously moved over a secondlocation of the second pattern of the electronic substrate. Once moved,material may be dispensed from the first and second dispensing units onrespective second locations of the first and second patterns.

In another exemplary embodiment, a method of dispensing material mayinclude (1) identifying positions of more than one location on anelectronic substrate, (2) determining whether a dispense location of afirst pattern and a dispense location of a second pattern are properlypositioned to perform simultaneous dispense operations on the first andsecond patterns based on the identified positions, (3) moving a firstdispensing unit to a dispense location on the first pattern and a seconddispensing unit to a dispense location on the second pattern, thedispense location of the first pattern corresponding with the dispenselocation on the second pattern, (4) dispensing at the first dispenselocation on the first pattern with the first dispensing unit and at thefirst dispense location on the second pattern with the second dispensingunit, and (5) repeating steps (3) and (4) for each remaining dispenselocation on the first and second patterns of the electronic substrate.As discussed above, prior to performing the method, a distance betweenthe first dispensing unit and the camera and the distance between thesecond dispensing unit and the camera may be calibrated.

Having thus described several aspects of at least one embodiment of thisdisclosure, it is to be appreciated various alterations, modifications,and improvements will readily occur to those skilled in the art. Suchalterations, modifications, and improvements are intended to be part ofthis disclosure, and are intended to be within the spirit and scope ofthe disclosure. Accordingly, the foregoing description and drawings areby way of example only.

What is claimed is:
 1. A dispensing apparatus comprising: a frameincluding a gantry configured to provide movement in X axis and Y axisdirections, the gantry including a beam configured to move in the Y axisdirection to achieve Y axis movement, the gantry further including acarriage mounted on the beam, the carriage being configured to movealong the length of the beam in the X axis direction; a support coupledto the frame, the support being configured to support at least oneelectronic substrate under the gantry; a first dispenser and a seconddispenser coupled to the carriage, the first dispenser and the seconddispenser each being configured to dispense material, one of the firstdispenser and the second dispenser being coupled to the carriage by anautomatic adjustment mechanism; an imager coupled to one of the frameand the gantry, the imager being configured to capture at least oneimage of a first pattern and a second pattern of an electronicsubstrate, the second pattern being substantially identical to the firstpattern; and a controller configured to control the operation of thegantry, the first dispenser, the second dispenser, the automaticadjustment mechanism, and the imager, wherein the automatic adjustmentmechanism is configured to move the one of the first dispenser and thesecond dispenser in the X axis direction to adjust a spacing between thefirst dispenser and the second dispenser during a dispensing operation,wherein the automatic adjustment mechanism includes a linear bearingsecured to the carriage, a mounting block configured to ride along thelinear bearing, coupled to the one of the first dispenser and the seconddispenser, and a first linear drive motor assembly configured to movethe mounting block along the linear bearing, wherein the controller isconfigured to use the at least one image to verify whether the firstpattern and the second pattern are properly positioned on the support,and wherein if the first pattern and the second pattern are not properlypositioned, the controller being configured to control the automaticadjustment mechanism to dynamically position the one of the firstdispenser and the second dispenser while continuing the dispenseoperation.
 2. The dispensing apparatus of claim 1, wherein the imager isconfigured to locate at least a portion of the electronic substrate andthe controller is configured to calculate a relative offset and rotationof the at least one portion of the electronic substrate.
 3. Thedispensing apparatus of claim 2, wherein the controller is configured tocalculate the relative offset based on images taken by the imager ofknown reference points.
 4. The dispensing apparatus of claim 1, whereina relative offset of at least a portion of the electronic substrate isdetermined during set up of the dispensing apparatus based on knownconfigurations.
 5. The dispensing apparatus of claim 1, wherein thedispensing operation comprises having the first dispenser and the seconddispenser dispense material on the electronic substrate.
 6. Thedispensing apparatus of claim 5, further comprising the first dispenserand the second dispenser simultaneously dispensing material on theelectronic substrate.
 7. The dispensing apparatus of claim 1, whereinthe first linear drive motor assembly includes a ball screw drivenlinear actuator, which is driven by a mechanically coupled motor.
 8. Thedispensing apparatus of claim 1, wherein the automatic adjustmentmechanism is further configured to move the one of the first dispenserand the second dispenser in the Y axis direction, and includes a firstbracket secured to the mounting block, the first bracket extending in adirection perpendicular to a direction of the linear bearing, and asecond bracket secured to the one of the first dispenser and the seconddispenser and configured to ride along the first bracket.
 9. Thedispensing apparatus of claim 8, wherein the automatic adjustmentmechanism further includes a second linear drive motor assemblyconfigured to move the second bracket along the first bracket.
 10. Thedispensing apparatus of claim 9, wherein the second linear drive motorassembly includes a ball screw driven linear actuator, which is drivenby a mechanically coupled motor.
 11. The dispensing apparatus of claim1, wherein, for each of the first dispenser and the second dispenser, aZ drive is configured to lower the dispenser when performing a dispenseoperation with the dispenser.